Air conditioning unit and air conditioning system for a vehicle

ABSTRACT

An air conditioning unit for a vehicle has an air conditioning casing having flow paths therein, an evaporator arranged in the air conditioning casing and substantially having a U-shape, an outer flow path provided on the outer side of the U-shaped evaporator on the upstream or downstream side of an air flow of the U-shaped evaporator, an inner flow path provided on the inner side of the U-shaped evaporator on the downstream or upstream side of the air flow of the U-shaped evaporator, and a heater core arranged on the downstream side of the air flow of the U-shaped evaporator.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No. P2003-024679 filed onJan. 31, 2003; the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an air conditioning unit for avehicle and an air conditioning system employing the air conditioningunit.

[0004] 2. Description of Related Art

[0005] Recent vehicles are equipped with an air conditioning systemcomponent in an instrument panel in front of a front seat. Theinstrument panel is usually provided with various electronic instrumentsof the vehicle, and such instruments restrict the space for the airconditioning system in the instrument panel.

[0006] Conventionally, an air conditioning system in an instrument panelof a vehicle is laid out by placing an air conditioning unit having anevaporator and a heater core at a widthwise center of the vehicle and byarranging a fan unit on the front passenger seat side of the airconditioning unit (for example, FIG. 26 of Japanese Unexamined PatentApplication Publication No. Hei-9-123748). This layout concentrates theevaporator and heater core at the widthwise center of the vehicle tosecure space in the instrument panel. This is called a centralizedlayout.

[0007] To meet a recent requirement for decreasing noise in vehiclecabins (passenger compartment), there is an increasing need to decreasenoise produced by vehicle air conditioning systems. Decreasing the noiseof an air conditioning system may be achieved by reducing an air flowrate of the air conditioning system. Reducing the air flow rate,however, deteriorates the performance of the air conditioning system.There is a necessity for an air conditioning system that achieves highair flow rates and low noise.

[0008] To achieve low noise and high air flow rates for an airconditioning system, the most effective way may be enlarging theventilating area of a heat exchanger (in particular, an evaporator) inthe air conditioning system. To enlarge the ventilating area, simplyincreasing, for example, the width of the evaporator leads to theincrease of a widthwise space occupied by the evaporator, to therebyincrease the size of the air conditioning unit. This makes it difficultto provide an installation space for the air conditioning system in avehicle and dose not substantially provide low noise and high air flowrates for the air conditioning system. In the centralized layout, thelarge evaporator prevents providing a foot space for a driver's seat ora glove box space in front of a passenger's seat.

[0009] An object of the present invention is to provide an airconditioning unit and air conditioning system for a vehicle, capable ofachieving low noise and high air flow rates and minimizing the outsidedimensions of the air conditioning unit.

SUMMARY OF THE INVENTION

[0010] In order to accomplish the object, an aspect of the presentinvention provides an air conditioning unit for a vehicle, including anair conditioning casing having flow paths therein, an evaporatorarranged in the air conditioning casing and having a substantiallyU-shape, an outer flow path provided on the outer side of the U-shapedevaporator on one of the upstream and downstream sides of an air flow ofthe U-shaped evaporator, an inner flow path secured on the inner side ofthe U-shaped evaporator on one of the downstream and upstream sides ofthe air flow of the U-shaped evaporator, and a heater core arranged onthe downstream side of the air flow of the U-shaped evaporator.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view schematically showing an airconditioning unit according to a first embodiment of the presentinvention;

[0012]FIG. 2 is a sectional view taken along a line II-II of FIG. 1;

[0013]FIG. 3 is a plan view schematically showing an air conditioningsystem for a vehicle formed by combining the air conditioning unit ofFIG. 1 and a fan unit;

[0014]FIG. 4 is a plan view schematically showing an air conditioningsystem for a vehicle formed by combining an air conditioning unitaccording to a second embodiment of the present invention and a fanunit;

[0015]FIG. 5 is a plan view schematically showing an air conditioningsystem for a vehicle formed by combining an air conditioning unitaccording to a third embodiment of the present invention and a fan unit;

[0016]FIG. 6 is a plan view schematically showing an air conditioningunit according to a fourth embodiment of the present invention;

[0017]FIG. 7 is a view showing a static pressure distribution in the airconditioning unit of the fourth embodiment; and

[0018]FIG. 8 is a view showing a static pressure distribution in anotherair conditioning unit for comparison with FIG. 7.

DETAILED DESCRIPTION OF EMBODIMENTS

[0019] Embodiments of the present invention will be described withreference to the accompanying drawings.

[0020] First Embodiment

[0021]FIGS. 1 and 2 show an air conditioning unit 1A according to thefirst embodiment of the present invention, and FIG. 3 shows an airconditioning system employing the air conditioning unit 1A and a fanunit 70. The air conditioning unit 1A includes a box-like airconditioning casing 10.

[0022] The air conditioning casing 10 incorporates an evaporator 50serving as a cooling heat exchanger to cool air. The evaporator 50 isvertically arranged in an upright posture and is configured in asubstantially U-shape in a plan view. In FIG. 3, the U-shaped evaporator50 is a combination of three flat evaporators 51, 52, and 53. The centerevaporator 51 is positioned at the center of the U-shape and the sideevaporators 52 and 53 are arranged on each side of the center evaporator51.

[0023] In the air conditioning casing 10, each ventilating face of theevaporators 51, 52, and 53 substantially orthogonally pass air becausean outer flow path and an inner flow path are provided on the outer andinner sides of the U-shaped evaporator 50, respectively. The outer flowpath consists of a center path 11 on the outer side of the centerevaporator 51 and side paths 12 and 13 on the outer sides of the sideevaporators 52 and 53, respectively. As a result, the outer flow path isa substantially U-shaped space in a plan view. The inner flow pathconsists of an inner center path 21 on the inner side of the centerevaporator 51 and inner side paths 22 and 23 on the inner sides of theside evaporators 52 and 53, respectively. As a result, the inner flowpath is a U-shaped space in a plan view. The inner side paths 22 and 23are defined by walls 22H and 23H spaced from the inner sides of theevaporators 52 and 53, respectively. The inner center path 21 is aspace.

[0024] According to the first embodiment, the outer flow path is on theupstream side of the U-shaped evaporator 50 in an air flow direction,and the inner flow path is on the downstream side thereof. On thedownstream side of the evaporator 50, a heater core 60 is arranged toserve as a heating heat exchanger to heat air. The heater core 60 is ina space on the inner side of the U-shaped evaporator 50. In FIG. 2, theheater core 60 leans toward a back ventilating face of the centerevaporator 51.

[0025] Between the center evaporator 51 and the heater core 60, a centerspace 25 is secured to merge air passing through the evaporator 50 andinner flow paths 21, 22, and 23 and guide the merged air to a frontventilating face of the heater core 60.

[0026] More precisely, the inner center path 21 is directly continuousto the center space 25, and the inner side paths 22 and 23 join thecenter space 25 through connections 22 e and 23 e, respectively.According to this embodiment, the center evaporator 51 and heater core60 are arranged closely adjacent to each other, and therefore, the innercenter path 21 is substantially the same as the center space 25.

[0027] In FIG. 2, a bypass 31 is formed over the heater core 60. Thebypass 31 directly guides at least part of the air introduced in thecenter space 25 into an air mixing space 26 by bypassing the heater core60. The bypass 31 has a butterfly bypass door 31D to open and close thebypass 31. The air mixing space 26 is behind (downstream side) theheater core 60, to mix the air passed through the bypass 31 with airpassed through the heater core 60.

[0028] The air conditioning casing 10 has a vent 32 and a foot outlet 34that are branched from the air mixing space 26. The vent 32 has a ventdoor 32D to open and close the vent 32. The foot outlet 34 has a footdoor 34D to open and close the foot outlet 34.

[0029] A downstream part of the foot outlet 34 is branched into a frontfoot outlet 35 and a rear foot outlet 36. Just above the bypass door31D, there is a defroster outlet 33 having a defroster door 33D.

[0030] The air conditioning casing 10 has an air inlet 14 to introduceair from the fan unit 70. The inlet 14 is arranged at a comer betweenthe center path 11 and the left path 12. The inlet 14 is so oriented asto directly guide air in an extending direction of the center path 11.

[0031] To install the air conditioning unit 1A in a vehicle, the fanunit 70 is arranged beside the air conditioning unit 1A, and the outletof the fan unit 70 is connected to the inlet 14 of the air conditioningunit 1A as shown in FIG. 3. In this state, the air conditioning unit 1Ais set at a widthwise center of an instrument panel in front of a frontseat in the vehicle. At this time, an opening of the U-shaped evaporator50 is oriented toward the rear of the vehicle, so that the fan unit 70may be on the passenger seat side.

[0032] Operation of the first embodiment will be explained. When the fanunit 70 is turned on, air from the fan unit 70 is guided into the airconditioning casing 10 through the air inlet 14. The air introduced intothe air conditioning casing 10 flows through the outer flow pathcomprising the center path 11 and side paths 12 and 13, the evaporators51, 52, and 53, and the inner flow paths 21, 22, and 23. During thisoperation, the air is dehumidified and cooled by the evaporators 51, 52,and 53. The conditioned air passed through the evaporators 51, 52, and53 flows through the inner flow paths 21, 22, and 23 and merges in thecenter space 25 in front of the heater core 60. The merged air in thecenter space 25 flows through the heater core 60 into the air mixingspace 26. The air that has flowed into the air mixing space 26 is blowninto the vehicle cabin from at least one of the outlets 32, 33, and 34that is open.

[0033] For example, in a full cool mode, the heater core 60 is not setto a heating mode. Namely, no heating medium is supplied to the heatercore 60, which therefore passes the conditioned air as it is. The bypassdoor 31D is closed or opened. As a result, the cooled air is blown intothe cabin.

[0034] In a heat mode, the heater core 60 is set to the heating mode.Namely, a heating medium is supplied to the heater core 60, which passesand heats the air, and the bypass door 31D is opened. As a result, theair passed through the evaporator 50 is heated by the heater core 60 andis blown into the cabin.

[0035] In an air mixing mode, the heater core 60 is set to the heatingmode, and the bypass door 31D is opened to directly guide part of theair passed through the evaporator 50 into the air mixing space 26. As aresult, the heated air passed through the heater core 60 and the cooledair passed through the bypass 31 are mixed with each other in the airmixing space 26, and the mixed air is blown into the vehicle cabin. Thetemperature of air to be blown into the cabin is adjustable bycontrolling the opening of the bypass door 31D.

[0036] The effect of the first embodiment will be explained. The airconditioning system for a vehicle according to the first embodimentemploys the substantially U-shaped evaporator 50. The center evaporator51 serves as a base, and the side evaporators 52 and 53 increase theventilating area, to thereby achieve low noise and high air flow rates.Compared with evaporators arranged in a horizontal row, thesubstantially U-shaped evaporator 50 has a reduced width. This minimizesthe width of the air conditioning casing 10, i.e., the width of the airconditioning unit 1A. Accordingly, the air conditioning system accordingto the first embodiment can achieve low noise and high air flow rates,and minimize the width of the air conditioning unit 1A.

[0037] The embodiment arranges the evaporator 50 and heater core 60 inupright postures, so that air may horizontally pass therethrough toachieve good heat exchanging performance.

[0038] The heater core 60 is forwardly inclined to enlarge theventilating area of the heater core 60 without increasing a spaceoccupied thereby. This increases the heat exchanging performance of theheater core 60.

[0039] The heater core 60 faces the center evaporator 51, to simplify aflow path layout and make the air conditioning unit 1A compact. Inparticular, the heater core 60 is arranged in an inner space of theU-shaped evaporator 50, to reduce the dimensions of the air conditioningunit 1A in a direction orthogonal to the heater core 60. According tothe embodiment, the dimensions of the air conditioning unit 1A arereduced in a front-rear direction of the vehicle.

[0040] Since the width of the air conditioning unit 1A is reduced asmentioned above, the air conditioning unit 1A and fan unit 70 can bearranged in the centralized layout as shown in FIG. 3 to sufficientlyprovide a foot space in front of a driver's sheet and a glove box spacein front of an passenger seat.

[0041] Second Embodiment

[0042] In the air conditioning unit 1A according to the firstembodiment, the bypass 31 and bypass door 31D are arranged over theheater core 60. On the other hand, an air conditioning unit 1B accordingto the second embodiment of the present invention shown in FIG. 4arranges bypasses 42 and 43 in inner flow paths 22 and 23, respectively.The bypasses 42 and 43 are provided with bypass doors 42D and 43D toopen and close the bypasses 42 and 43, respectively.

[0043] The bypass doors 42D and 43D are opened to guide cooled airpassed through the evaporators 52 and 53 into an air mixing space 26where the cooled air is mixed with heated air passed through a heatercore 60.

[0044] Third Embodiment

[0045]FIG. 5 shows an air conditioning unit IC according to the thirdembodiment of the present invention. The third embodiment has no bypass.The third embodiment entirely passes all the air from evaporators 51,52, and 53 through a heater core 60. In this case, the temperature ofthe air is adjusted by controlling the flow rate of a heating mediumsupplied to the heater core 60.

[0046] Fourth Embodiment

[0047]FIG. 6 shows an air conditioning unit 1D according to the fourthembodiment of the present invention. This embodiment shapes flow pathsin an air conditioning casing 10 so as to smooth air flow and improveair-conditioning performance.

[0048] The air conditioning unit 1D of the fourth embodiment has acontraction (step) 15 at a connection between an air inlet 14 and acenter flow path 11, to increase air distribution to the left path 12.

[0049] In addition, each of the left and right paths 12 and 13 istapered so as to become narrower toward the front end thereof. Accordingto this embodiment, outer walls 12H and 13H of the left and right paths12 and 13 are tapered and constricted toward the front ends of the paths12 and 13. Instead of slanting the outer walls 12H and 13H, sideevaporators 52 and 53 may be widened to narrow the side paths 12 and 13toward the ends thereof.

[0050] Further, a comer 16 between the center path 11 and the right path13 is rounded by a curved outer wall 16H. The outer wall 13H is inwardlycurved continuously from the curved wall 16H.

[0051] Moreover, at intersections between a center evaporator 51 and theside evaporators 52 and 53, smoothers 55 and 56 are attached to smooththe air flow. Inner side paths 22 and 23 are provided with bypasses 22a, 22 b, 23 a, and 23 b.

[0052]FIG. 7 shows a static pressure distribution in the airconditioning unit 1D of the fourth embodiment, and FIG. 8 shows a staticpressure distribution in an air conditioning unit 1E serving as acomparison example (the air conditioning unit 1E resembles the airconditioning unit 1A of the first embodiment).

[0053] Comparing FIGS. 7 and 8 with each other, it is understood thathigh static pressure components are averaged in the air conditioningunit 1D of FIG. 7 and a uniform static pressure is achieved just afterthe evaporator 50. This will be explained in more detail.

[0054] In the air conditioning unit 1E of FIG. 8, air from an air inlet14 mostly tends to flow into a center path 11 instead of a left path 12due to inertial. In the air conditioning unit 1D of FIG. 7, thecontraction 15 is at the connection between the air inlet 14 and thecenter path 11, to properly adjust an air distribution and providesufficient air to the left path 12 also.

[0055] In the air conditioning unit 1E of FIG. 8, a comer 16 from thecenter path 11 to a right path 13 and the front ends of the side paths12 and 13 are substantially dead ends for air flow. Accordingly, due tothe large force provided from the fan unit 70 and large flow resistanceby evaporators 51, 52, and 53, the dead ends form high-pressure zones(hatched zones A and B). This causes an uneven flow rate distributionaround the evaporators 51, 52, and 53. On the other hand, the airconditioning unit 1D of FIG. 7 promotes a smooth flow of air as shown inFIG. 7 and improves static pressure distributions in front of and behindthe evaporator 50.

[0056] In each of the above embodiments, the evaporator is arranged insubstantially a U-shape. The present invention also allows otherarrangements in which the side evaporators are not completely orthogonalto the center evaporator.

[0057] The present invention has been explained in detail with referenceto the embodiments. As is apparent for those skilled in the art, theseembodiments are not intended to limit the present invention. The presentinvention is achievable in other forms without departing from the spiritand scope thereof specified in the appended claims. This specificationserves only for exemplary explanation of the present invention and isnot intended to restrict the present invention.

[0058] As disclosed, the invention employs an evaporator substantiallyhaving a U-shape. Unlike evaporators arranged in a horizontal row, theU-shaped evaporator has a short width and an increased ventilating area.This configuration achieves low noise and high air flow rates andminimizes the width of an air conditioning casing or an air conditioningunit.

[0059] The invention combines a plurality of flat evaporators into aU-shaped evaporator, which is easy to manufacture.

[0060] Three flat evaporators are combined into a substantially U-shapedevaporator, which is easy to manufacturer and has a simplest structure.

[0061] A heater core is arranged to face a central one of theevaporators arranged in a U-shape. This configuration provides the airconditioning unit with simple flow paths and a simple structure.

[0062] The heater core is arranged in a space on the inner side of theU-shaped evaporator, to reduce the dimensions of the air conditioningunit. The evaporator and heater core may be installed in a front-reardirection of a vehicle to reduce the dimensions of the air conditioningunit in the front-rear direction.

[0063] The heater core is inclined relative to the center evaporator, toincrease the ventilating area and heat-exchanging capacity of the heatercore without increasing a space occupied by the heater core.

[0064] The evaporator and heater core are arranged in upright posturesto horizontally pass air therethrough, thereby improving heat-exchangingperformance. The heater core may be inclined so that a top end of theheater core is closer to the center evaporator and a lower end of theheater core is farther from the center evaporator. In this case, theheater core leans toward the center evaporator so that air passedthrough the heater core may flow upwardly. This is advantageous when anoutlet of the air conditioning unit is positioned above the heater core.

[0065] Air is passed through the center evaporator and side evaporatorsinto a center space and then through the heater core. Namely, the airpassed through the evaporators is entirely passed through the heatercore. In this case, the temperature of the air is adjustable bycontrolling the quantity of heating medium supplied to the heater core.

[0066] A bypass door may be opened to blow part of the conditioned airpassed through the evaporator into a vehicle cabin by bypassing theheater core.

[0067] A bypass may be formed over the heater core. A vent may be formedon a top face of the air conditioning unit, to blow cooled air passedthrough the evaporator from the vent. This configuration improves themaximum flow rate of cool air passing through the vent.

[0068] The bypass doors may be opened to directly blow part of theconditioned air passed through the side evaporators into the cabin bybypassing the heater core.

[0069] An air mixing space is provided downstream from the heater core,to mix conditioned air passed through the bypass with conditioned airpassed through the heater core. The bypass door is controllable toadjust a mixing ratio of the cool air and hot air and control thetemperature of air blown from an outlet of the air conditioning unitinto the cabin.

[0070] The air mixing space is provided downstream from the heater core,to mix conditioned air passed through the bypass with conditioned airpassed through the heater core. The bypass door is controllable toadjust a mixing ratio of the cool air and hot air and control thetemperature of air blown from an outlet of the air conditioning unitinto the cabin.

[0071] An outer flow path is provided on the outer side of theevaporator. The outer flow path is a U-shaped space in a plan view,comprising of a center path provided on the outer side of the centerevaporator and side paths provided on the outer sides of the sideevaporators, respectively. At a corner where the center path connects toone of the side paths, an air inlet is arranged to straightly guide airin an extending direction of the center path. The air inlet isconnectable to an outlet of a fan unit. This enables the fan unit to bearranged beside the air conditioning unit. The air conditioning unit andfan unit may be installed side by side in a width direction of thevehicle, to minimize a space in the front-rear direction of the vehicleoccupied by an air conditioning system composed of the air conditioningunit and fan unit. With this configuration, the fan unit can properlysend air to the evaporator through the space (outer flow path) having aU-shape in a plan view provided on the outer side of the evaporator.

[0072] A path contraction is provided at a connection between the airinlet and the center path, to increase air distribution to one side path(the side path closer to the air inlet). This configuration sufficientlysends air to the side path. Namely, air from the air inlet tends tomostly flow to the center path instead of the side path due to inertia.At this time, the path contraction at the connection properly controlsair distributions.

[0073] The first and second side paths are tapered to make them narrowertoward the front ends thereof, thereby properly distributing air to theevaporator. The front end of each path is a substantial dead end for airflow, and therefore, the fan unit sends air having a large pressingforce into the center path. At this time, the evaporator demonstrateslarge air resistance, and the dead ends produce high pressure to make aflow rate distribution of air passed through the evaporator uneven. Thepath shapes of the present invention can smooth an air flow and improveflow rate distributions.

[0074] An outer wall is rounded to provided a curved path along a comerbetween the center path and one of the side paths, to further improveflow rate distributions. The comer between the center path and the sidepath forms a substantial dead end for air flow. As a result, the comercauses high pressure to make an uneven flow rate distribution of airpassed through the evaporator. The curved path mentioned above cansmooth the air flow and improve flow rate distributions.

[0075] A smoother part (round part) is arranged at each of theintersections between the center evaporator and the side evaporators, tosmooth the air flow. This further improves the flow rate distribution.

[0076] The air conditioning unit is arranged at a widthwise center ofthe vehicle with the fan unit beside the air conditioning unit. Namely,the air conditioning unit is arranged at the widthwise center of thevehicle and the fan unit on the front passenger seat side. This makesthe air conditioning system compact in front-rear and verticaldirections in the vehicle. Accordingly, the air conditioning system canproperly be installed in an instrument panel of the vehicle.

[0077] Unlike evaporators arranged in a horizontal row, the evaporatorminimizes an installation width and enlarges a ventilating area. Thisresults in minimizing the width of an air conditioning casing or an airconditioning unit and achieves low noise and high air flow rates. Theair conditioning unit and a fan unit may be installed in a widthdirection in a vehicle, to make the air conditioning system compact invertical and front-rear directions in the vehicle. Therefore, the airconditioning system can properly be installed in an instrument panel ofthe vehicle.

[0078] The evaporator and a heater core are provided at a widthwisecenter of the instrument panel. This configuration provides foot spacefor the driver's seat and passenger seat.

What is claimed is:
 1. An air conditioning unit for a vehicle,comprising: an air conditioning casing having flow paths therein; anevaporator arranged in the air conditioning casing and havingsubstantially a U-shape; an outer flow path provided on an outer side ofthe U-shaped evaporator on one of an upstream and downstream sides of anair flow of the U-shaped evaporator; an inner flow path provided on aninner side of the U-shaped evaporator on one of the downstream andupstream sides of the air flow of the U-shaped evaporator; and a heatercore arranged on the downstream side of the air flow of the U-shapedevaporator.
 2. The air conditioning unit of claim 1, wherein: theU-shaped evaporator is formed of a plurality of evaporators.
 3. The airconditioning unit of claim 2, wherein: the U-shaped evaporator is formedof a center evaporator and side evaporators arranged on each side of thecenter evaporator.
 4. The air conditioning unit of claim 3, wherein: theouter flow path is on the upstream side of the air flow of the U-shapedevaporator and the inner flow path is on the downstream side of the airflow of the U-shaped evaporator; and the heater core is arranged to facethe center evaporator.
 5. The air conditioning unit of claim 4, wherein:the heater core is arranged in a space defined on the inner side of theU-shaped evaporator.
 6. The air conditioning unit of claim 5, wherein:the heater core is inclined relative to the center evaporator of theU-shaped evaporator and is arranged to face the center evaporator. 7.The air conditioning unit of claim 6, wherein: the U-shaped evaporatoris arranged in an upright posture and the heater core is inclinedrelative to the center evaporator and is arranged to face the centerevaporator.
 8. The air conditioning unit of claim 4, further comprising:a center space provided between the center evaporator and the heatercore, configured to merge air flowing in the inner flow path so that themerged air in the center space may be entirely passed through the heatercore.
 9. The air conditioning unit of claim 4, further comprising: acenter space provided between the center evaporator and the heater core,configured to merge air flowing in the inner flow path and pass themerged air through the heater core; a bypass configured to guide part ofthe air in the center space toward a downstream space behind the heatercore by bypassing the heater core; and a bypass door arranged in thebypass, configured to open and close the bypass.
 10. The airconditioning unit of claim 4, further comprising: a bypass formed for aninner flow path provided for each of the side evaporators, configured todirectly guide at least part of the air passed through the sideevaporators into a downstream space behind the heater core by bypassingthe heater core; and a bypass door arranged in the bypass, configured toopen and close the bypass.
 11. The air conditioning unit of claim 9,further comprising: an air mixing space provided on the downstream sideof the heater core, configured to mix air passed through the bypass withair passed through the heater core.
 12. The air conditioning unit ofclaim 10, further comprising: an air mixing space provided on thedownstream side of the heater core, configured to mix air passed throughthe bypasses with air passed through the heater core.
 13. The airconditioning unit of claim 5, wherein the outer flow path provided onthe outer side of the evaporator is a U-shaped spacecomprising a centerpath provided on the outer side of the center evaporator and first andsecond side paths provided on the outer sides of the side evaporators,respectively, the air conditioning unit further comprising: an air inletformed at a comer where the center path connects to the first side path,configured to guide air in a straight extending direction of the centerpath.
 14. The air conditioning unit of claim 13, further comprising: apath contraction formed at a connection between the air inlet and thecenter path, configured to increase air distribution to the first sidepath.
 15. The air conditioning unit of claim 13, wherein: the first andsecond side paths are tapered so as to become narrower toward front endsthereof.
 16. The air conditioning unit of claim 13, further comprising:a comer path curved along a comer between the center path and the secondside path, the comer path being curved by rounding an outer wall of thecomer path.
 17. The air conditioning unit of claim 13, furthercomprising: a smoother arranged at each intersection between the centerevaporator and the side evaporators, configured to smooth an air flow.18. The air conditioning unit of claim 13, wherein: the air conditioningunit is arranged at a widthwise center of the vehicle in an instrumentpanel in front of a front seat of the vehicle so that an opening of theU-shaped evaporator and the heater core are oriented to the rear of thevehicle and so that the air inlet is oriented in a widthwise directionof the vehicle.
 19. An air conditioning system for a vehicle, comprisingan air conditioning unit and a fan unit, the air conditioning unitincluding: an air conditioning casing having flow paths therein; anevaporator arranged in the air conditioning casing and havingsubstantially a U-shape; an outer flow path formed between the U-shapedevaporator and the air conditioning casing along the U-shapedevaporator, the outer flow path having a center path and first andsecond side paths and a substantially U-shape, and being upstream fromthe U-shaped evaporator in an air flow direction; an inner flow pathprovided on the inner side of the U-shaped evaporator downstream fromthe U-shaped evaporator in the air flow direction; a heater corearranged downstream from the U-shaped evaporator in the air flowdirection; and an air inlet provided for the air conditioning casing ata comer between the center path of the outer flow path and the firstside path of the outer flow path, configured to guide air in a straightextending direction of the center path, the U-shaped evaporator beingarranged to open toward a rear of the vehicle, the air inlet beingoriented in a widthwise direction of the vehicle, the air conditioningunit and the fan unit being arranged side by side in the widthwisedirection of the vehicle.
 20. The air conditioning system of claim 19,wherein: the air conditioning unit is arranged at a widthwise center ofthe vehicle in an instrument panel in front of a front seat of thevehicle, and the fan unit is arranged beside the air conditioning unitin the widthwise direction of the vehicle.